Plug insert for bore holes for cushion blasting in gaseous mines



July 4, 1939. F; STRUZIK 2,164,690-

PLUG INSERT FOR BORE HOLES FOR CUSHION BLASTING'IN GASEOUS MINES S21/w z/ July 4, 1939.

F. STRUZIK PLUG INSERT FOR BQR HOLES FOR CUSHION BLASTING IN GASEOUS MINES Filed April 5o, 19:57

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2.134,69@ PLUG INSERT FR MRE HLES FOR ION BLASG EN GASEUUS Frantiek S Petrvald, Caeclioslov signor of one-third to .loser Dvorak, More. Ostrava-Vitkovice, Chodska, and one-third to si Ustrava-Zabreln, Mora Czechoslovakia,

el Pokorny, Moravska 1i Caechoslovaha application anni so, i937, sensi Nn. 140.044

In Czechoslovakia if- According to the safety regulations oi minesomces with regard to cushion shots in mines with lire damp, the use of incombustible material as inserts for filling the spaces before and behind the charge in the shot hole is permitted. These inserts-so called spare cartridges-consist of hollow cylinders made of pasteboard, inserts of cross framed sections, ribs of wires, etc.. bywhich the connection to the outside of the bore-hole is kept open for the isolated electric wire. The shot hole fully charged and provided with spare cartridges is stemmed with clay.

All disadvantages of prior blasting means are eliminated by the use of plug inserts according to my invention which consists of inserting and packing the plug inserts which are made of incombustible material, in soft clay plugs or clay bells which on being inserted into the bore holes do not cause any ignition friction nor do any damage to the insulated wiring so that the plugs are absolutely safe and reliable and moreover very simple.

- The accompanying drawings show the constructional form of my invention.

- Fig. l is a longitudinal section of the shot hole including the charge when using clay plugs with disc inserts;

Fig. 2 shows a modification in which a disc insert is wedged in the bore hole to form a sustaining means for the explosive charge;

Figl 3 shows the means employed for wedging` the iiat disc insert in a bore hole;

Fig. 4 shows the means for introducing a ilat insert to the required depth by means of a ramming member;

Fig. 5 is a longitudinal section showing the insertion of a-plug in a shot hole by the wedging -action of the at insert;

Fig. 6 is a sectional view of plug shown in Fig 5;

' Fig. 13 isa front view of thevdisc shaped plugv insert, and

Fig. 14 is a side view of the same, The round plug insertion according to my inusing clay plugs with A vention consists of a at incombustible disc I of asbestos or similar material having a hole 2 in the middle through which an incombustible cord 3 can be drawn. 'I'he end of the cord 3 drawn through insertion I is provided with knots 4 and 5 to prevent slipping through hole 2. The entire insertion I together with the knotted end of cord 3 is inserted and packed in a corresponding piece of soft clay or earthenware which is then formed in a plug E. A

The cord 3 and the second knot Sand the part of the cord end between the knots 4 and 5 constitute a valuable stiiening of the clayplugs. Should a thick layer o f soft clay of the same diameter as plug 6 be required around insertion I, insertion I is then inserted diagonally into plug 6. 'I'he soft plug 6 prepared in the above manner together l with insertion I is then pluggedto a certain depth in the shot hole which is provided with charge 8 and conducting wires 9-Flg.-9. Plug 6 and insertion lare xed by cord 3 deep enough in shot hole 'I so that betweenplug I5 and charge U the necessary exploding space is kept free and plug is kept iirm, While by means of rammer Ill the soft plug 6 is forced into shot hole l. The remaining part of the mouth of the shot hole I is iilled up and sealed by means of the usual clay substances II- bringing the shot hole into readiness. for blasting.

Figs. 13 and 14 show a plug insert for shot hole 1 with greater diameter, Same consists of an incombustible flat disc of asbestos or similar material the longer middle axis of which is a little greater than the diameter of shot hole 1.

The shorter sides of disc I2 are iitted to shot hole l by corresponding rounding oi of latter. .(Fig. 6.) One end of disc I2 is provided with two holes close together through which electric wire I4 .is drawn, being threaded in at one `hole and out at the other so that both ends of cord I iind themselves on the same side 'of plug insert I2. The insert I2 together with inserted cord Id are then placed and sealed in soft clay plug 6 according to Fig. '1, thus making the soft plastic plug ready for use. The finished clay plug is then inserted in the usual manner to a certain depth in shot hole l. Both ends of cord It are then taken hold of and plug 6 is driven into the shot hole by means of rammer l whereby by appropriate pulling at cord It, insert I2 embedded in the clay plug mass, is raised and the charge exploded in shot hole I y as illustrated in Fig. 5.

After raising insert I2 and exploding one end ther use by means of the other end. 'Ihe insert I2 may be employed in the shot hole in any position thought suitable, e, g., vertically, horizontally, etc., whereby besides insert yI2 sufiicient space remains free for electric wires 9 in the clay mass of the plug-Fig. 6-so that same can not be damaged. 1

On plug 6 the usual clay material Il is then pressed into shot hole 'I and the latter sealed- Fig. 1.

In the same way as disc insertion I2, the round insertion I may be provided with either two holes near each other or besides the middle hole 2 also a groove I5-Fig. 3--or something similar for the removal of electric wire. .iThe plug inserts vabove described are made of asbestos and are extremely simple and very light so that any number of same may be carried in the pockets, etc.,

without danger of breakage, and the entire plug of soft clay which is prepared at the place of using remains perfectly soft and plastic s o that no damage of electric wire insulation may be "caused, by the plug nor is any premature explo-l sion of the charge by riction possible.

The plug inserts along withthe clay housing may also be used as a support in shot hole I behind charge 8 in place of the spare inserts used at the present time behind the charge. As shown in Figs. 3 and 4 the insert l2 is introduced into the shot hole to a certain depth by means oi' the' usual rammer ID which has acorres'pon'ding groove I B the size of -insert I2 and a cross groove I1 for the leading cord of insert I2. After the introduction of plug insert, rammer I0 is withdrawn a little way, whereby through tightening the cord 4 and pushing rammer Il! the support I2 is raised in the shot hole and solidly wedged -in accordance with Fig. 3 so that the cord may be removed. Now the charge 8 is forced into shot .hole 1 up to the support I2 and the shot hole `closed in the prescribed manner.

' 4In this way any additional space required in the shot hole without using present day spare inserts may be achieved before and behind the charge. v'I lie cord I4 of support I2 may also serve very well in this case for drawing back charge8 in the shot hole according to Fig. 10. For this purpose a sling I8 is formed on the taut cord I4 which is drawn throughthe holes I3 in the-solidly wedgedinsert I2 and the charge4 l is inserted, which may then be drawn into shot hole 1 up to insert I2 by pulling on the other end of cord I4, according to Fig. 2

,The further pieces of charge 8 are brought into the shot hole in' the same way, quitev close together or, if desired, following each other at certain intervals which may be measured exactly by cord I4.

This sort of loading is especially appropriate I or steep shot holes as the whole charge really hangs here on insert I2 so that the charge can not fall out before closing the shot/hole.

The introduction o! charge 8 toa certain depth in a horizontal shot hole can also be made with rammer I0 alone according to Fig. 4 which for this purpose is provided with separating notches or, cuts IB. e. g., at 10 cm. distance from each other. With the aid of the separating-notches I 5 the necessary depths for introduction oi charge 8 maybe exactly determined. For marking different depths rammer I0 is provided with sliding ring I5 by which a too deepinsertion of rammer I0 and thereby also of charge 8 into shot hole 1 is prevented. In this way the charge may be distributed in the shot hole as required without the use of spare inserts.

I I claim:

1. A plug for a. shot hole for blasting comprising the combination of a cylindrical flat insert of incombustible material provided with an opening, a pulling member comprising a ilexible cord anchored in said opening, and a plastic body formed around and embedding Said insertand the anchored portion of the cord. l

-2. A plug for a shot hole for blasting comprising the combination of a. flat insert of incombustible material provided with openings offset with respect to the medial portion of said insert, a pulling member comprising a ilexible cord threaded through the openings. and a plastic bodyformed around and embedding said insert and the portion of the ,cord threaded through Said openings.

3. A plug insert for a shot hole for blasting comprising a :dat insert having' parallel4 sides -and a widthless than the diameter of the shot hole, the length of said insert being greater than spect to the medial portion of the insert and adapted to receive a. exible pulling member threaded through said openings.

4. A plug for a shot holefor -blasting comprising the combination of a nat insert of incombustible material provided with an opening there.- in, a pulling member comprising a flexible cord anchored in said opening, and a cylindrical plastic body formed around and embedding said insert and the anchored portion of the cord, said insert being embedded in the plug in a plane transversely inclined to the axis of the plug.

5. Means for supporting an explosive charge in a shot hole comprising in combination with a ramming vmember having a notch formed in the end thereof and a longitudinally extending groove,

lof a ilat insert of incombustible material receivable in said slot and conilned between the latter and the wall of the shot hole, said insert having a pair of adjacently disposed openings oiset with respect to the medial portion of said insert, and a pulling member comprising a ilexible cord threaded through the openings and extend along the longitudinally extending grooves of the ram I ming member, s o that on pulling the exlble cord the insert will be wedged in the shot hole at the position determined bythe end of the ramming member `within the shot hole;

, 6. A method oliv charging an upwardly inclined shot hole by means of an insert having a longitudinal dimension slightly greater than the shot hole and a cord slidably threaded through said insert consisting in rammingthe insert into predetermined position in the shot hole, wedging the insert in said shoifhole, fastening the explosive charges at spaced intervals to one end of said cord, pulling the other end of said cord to draw the explosive charges into the shot hole, and sealing theshot hole.

' :a-ANTISEK STRUZK. 

